Motor vehicle trailer coupling

ABSTRACT

A trailer coupling for motor vehicles has a bar, a ball provided on the bar, the bar being automatically adjustable between an idle position and an operating position, and an adjusting drive including an electric motor which automatically adjust the bar between the idle position and the operating position.

BACKGROUND OF THE INVENTION

The invention relates to a trailer coupling for motor vehicles with abar on which a ball is located in the usual manner.

As long as trailer couplings are not used the ball-bar protruding beyondthe rear bumber disturbs. For solving this problem trailer couplings areknown whose ball-bar may be disassembled. It has been found that thedisadvantage of the known trailer couplings is that the disassembly ofthe ball-bar is physically very demanding.

BRIEF SUMMARY OF THE INVENTION

It is the object of the invention to put forward a trailer couplingwhich does not have this disadvantage.

The object is solved by the features of patent claim 1.

Further advantageous formations of the invention are described in thedependent claims 2 to 8.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail by way of a preferredembodiment form with reference to the drawings, wherein furtheradvantageous details can be deduced from the drawings. The same partswith regard to their function are provided with the same referencenumerals.

The drawings show individually:

FIG. 1 an elevation of the trailer coupling according to the invention,with an axial adjustment into the idle position,

FIG. 2 a lateral view of the trailer coupling according to the inventionand according to FIG. 1,

FIG. 3 a lateral view of a ball-bar according to FIG. 1,

FIG. 4 an elevation of a sleeve for receiving the ball-bar according toFIG. 3,

FIG. 5 a lateral view of the sleeve according to FIG. 4,

FIG. 6 a view according to arrow A in FIG. 5,

FIG. 7 a lateral view of an alternative embodiment form with a pivotableball-bar,

FIG. 8 a section according to line B—B of FIG. 7, through the drive ofthe ball-bar,

FIG. 9 a lateral view of a further embodiment form with a laterallypivotable coupling bar, and

FIG. 10 a plan view of the embodiment form according to FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 the adjustable trailer coupling is indicated at 1. It consistsessentially of an axially adjustable bar 2 whose outer end carries aball 3 as well as a guiding sleeve 4, a motor with planet gears 6, aspur gear 7 and an adjusting spindle 8.

The guiding sleeve 4 on both sides carries in each case an assemblyflange 9 in which there are incorporated threaded bores 10. The wholetrailer coupling 1 is assembled onto a vehicle in that by way of screwsit is fastened onto a suitable bracket of the vehicle. With this screwsengage into the threaded bores 10.

The bar 2 is accomodated by the guiding sleeve 4. For this purpose thebar 2 comprises a rear guiding surface 11 and a front guiding surface 12which via a cone 13 blend into a somewhat slimmer bar 2.

Furthermore in the guiding sleeve 4 an annular inner cone 14 isfastened. Finally in the guiding sleeve 4 there are formed guiding slots15.

On the bar 2 in the rear region there is fastened a pin-like connectingrod 16 which engages into the guiding slot 15. Furthermore in the bar 2there is incorporated a pocket hole with an inner thread 17.

The adjusting spindle 8 is screwed into the mentioned inner thread 7 andis rotated by an electrical motor via the spur gear 7 as well as theplanet gear 6. The individual gearwheels of the gear 7 are mountedbetween lateral plates 19 and 20. The housing of the planet gear 6 andthe guiding sleeve 4 are rigidly connected to the plate 20. Theadjusting spindle 8 is likewise rotatably mounted in the plates 19 and20 so that it can be rotated by the electrical motor 5 as desired.

If the motor 5 is driven in the corresponding direction, then theadjusting spindle 8 also rotates. At the same time the bar 2 which isarranged as a nut on the adjusting spindle 8 and is secured againstrotation by the connecting member 16 is pushed outwards. With this axialmovement the bar 2 is guided in the guiding sleeve 4 by the guidingsurfaces 11 and 12. The bar reaches its end position when the outer cone13 sits rigidly in the annular inner cone 14.

As long as the guiding slots 15 run in the axial direction, the bar 2maintains its radial position. After roughly half the adjusting distancethe guiding slots 15 blend into a spiral-shaped course. This results inthe fact that the bar 2 on extending then correspondingly turns so thatthe ball 3 in the operating position points vertically upwards. Theoperating position is shown in FIGS. 1 and 2 by dashed lines.

For a better understanding the essential parts are again individuallyshown in FIGS. 3 to 6.

An alternative embodiment form of a trailer coupling is shown in FIG. 7.With this embodiment form the bar 2 is not axially displaced, but ispivoted about an axis 24.

For an easier understanding only the bar 2 with its pivoting drive 21 isshown, wherein known additional drive parts such as a gear motor, arenot shown.

FIG. 7 shows a pivoting drive 21 with which the bar 2 can be pivotedupwardly about approximately 90° .

The drive however can in a slightly modified form serve for passingthrough other pivoting angles.

With a correspondingly modified installation location, and an adaptedbar 42 for this, a modified pivoting drive 41 may also be applied for ahorizontal pivoting of the bar 42. Such a pivoting drive 41 is shown inthe FIGS. 9 and 10.

With the embodiment shown in FIG. 7 the bar 2 however is pivotedvertically upwards. For this purpose it is pivotably mounted between twoplates 22 and 23 about the axis 24 on the pintail 25.

Furthermore the bar 2 comprises a limb 26 whose function can be seenfrom FIG. 8.

In FIG. 8 a section corresponding to the marking effected in FIG. 7 isshown. In the region of the limb 26 the bar 2 is thus provided with aslot 27. Furthermore perpendicular to the plane of the slot there isprovided a bearing bore 28 for the pintail 25, a bearing bore 29 for apinion shaft 31 as well as a bore with an inner thread 30 for a blockingcone 32.

As mentioned the pintail 25 is rotatably mounted between two plates 22and 23. In the region of the slot 27 of the bar 2, the pintail 25comprises a toothing 33. A gearwheel 34 engages into this toothing 33,the gearwheel being mounted on the pinion shaft 31. With the gearwheel34 there meshes a further gearwheel 35 which is connected to a shaft 36in a rotatably rigid manner.

On the shaft 36 on both sides of the gearwheel 35 there is each mounteda blocking cone 32 in a rotatably rigid but axially displaceable manner.This blocking cone 32 comprises an outer thread 37 which engages intothe inner thread 30. For the blocking cone 32 a locking opening 38 isprovided in the plates 22 and 23.

In the position shown in FIG. 8 the blocking cone 32 should be retractedin the usual manner into the locking opening 28. For a betterrecognition it is shown in a position in which the bar 2 may be pivoted.

The ends of the pinion shaft 31 are guided in arc-shaped slots 39 of theplates 22 and 23. The remaining bores of the plate 22 shown in FIG. 7serve for its fastening onto the vehicle or serve the fastening of afurther gear with a suitable electrical drive or the connection by wayof distance bolts.

The position of the bar 2 represented in FIG. 7 with dashed linescorresponds to its operating position. For pivoting the bar 2 then, agearwheel 40 rigidly connected to the pintail 25 is driven. Sincefirstly the blocking cone 32 is retracted into the locking opening 38 ofthe plate 23, the bar 2 can still not be pivoted about the axis 24.Instead of this via the toothing 33 and via the gearwheel 34 thegearwheel 35 is rotated. Since this gearwheel is rigidly connected tothe shaft 36, the shaft 36 drives the blocking cone 32. Since the outerthread 37 of the blocking cone is engaged with the inner thread 30, atthe same time the blocking cone 32 moves axially inwards until it iscompletely extended out of the locking opening 38. As soon as theblocking cone 32 comes to bear on the gearwheel 35, the gearwheel 35 andthe gearwheel 34 which is engaged with it are blocked. By way of thisthe pintail 25 drives the blocked gearwheel 34 and the pinion shaft 31,so that the pinion shaft 31 is pivoted about the axis 24. At the sametime the pinion shaft 31 which is mounted in the bearing bore 29 of thebar 2 then drives this bar so that the bar 2 is pivoted. This pivotingmovement finishes as soon as the pinion shaft 31 reaches the end of theslot 39.

For the purpose of clarity it must be mentioned that in FIG. 8 the leftblocking cone is not shown.

For the electrical drive it is provided for this to be switched off assoon as the laod exceeds a previously set limiting value. In this waydamages are avoided, in the case that on moving the bar 2 foreign bodiesshould inhibit the further operation. So that the adjustment cannot beinitiated during the journey of the vehicle it is furthermore providedfor the trailer coupling to only be able to be operated outside thecompartment of the vehicle. It is particularly advantageous when theoperating means, for example a switch, is arranged in the boot of thevehicle.

In this manner there is created a vehicle coupling which is easily andcomfortably brought into a position in which it no longer disturbs.

What is claimed is:
 1. A trailer coupling for motor vehicles, comprisinga towing bar formed so as to be axially displaceable between an inoperative position and an operating position; a spindle and nut drivefor displacing said towing bar between said positions, said towing barbeing formed as a part of said spindle and nut drive; and a motor withwhich said towing bar is connected for displacement of said towing bar,said towing bar being formed so as to be rotatable about its axis.
 2. Atrailer coupling as defined in claim 1, wherein said towing bar has anaxial bore with an internal thread serving as a nut of said spindle andnut drive.
 3. A trailer coupling as defined in claim 2, wherein saidspindle/nut has a spindle formed as a threaded rod which is locatedinside said axial bore of said towing bar.
 4. A trailer coupling asdefined in claim 3, wherein said spindle has a drive motor.
 5. A trailercoupling as defined in claim 4, wherein said drive motor is an electricdrive motor.
 6. A trailer coupling as defined in claim 1, wherein saidtowing bar is formed so as to lock automatically in said operatingposition.
 7. A trailer coupling as defined in claim 1, and furthercomprising a link guide for rotation of said towing bar.
 8. A trailercoupling as defined in claim 1; and further comprising a coupling piecefor an electrical supply of a trailer, said coupling piece beingassociated with said bar and also being displaceable.
 9. A trailercoupling as defined in claim 8, wherein said coupling piece ispower-displaceable.
 10. A trailer coupling as defined in claim 1,wherein said bar has a drive which is operable via an effectiveconnection and has a switch disposable outside of a passenger cell of avehicle.
 11. A trailer coupling as defined in claim 10, wherein saidswitch is disposable in a large compartment of the vehicle.
 12. Atrailer coupling for motor vehicles, comprising a bar which isswivelable between an inoperative position and a locked horizontaloperating position; and at least one drive provided for swivelinglocking and unlocking motions of said bar, said at least one drive beingformed so that it positively locks and unlocks automatically uponswiveling into or out of said operating position, wherein the bar isswivelable from said operating position into said inoperative positionupwardly or horizontally about 0° or 90°.
 13. A trailer coupling asdefined in claim 12, wherein said at least one drive is formed as anelectric drive motor.
 14. A trailer coupling as defined in claim 12; andfurther comprising a driving axle on which said bar is rotatablysupported; and a pinion shaft which engages into said driving axle anddrives said bar.
 15. A trailer coupling as defined in claim 12; andfurther comprising a locking cone displaceably supported in said bar andformed so as to lock said bar automatically in said operating position.16. A trailer coupling as defined in claim 5, wherein said bar has apinion shaft; and a spindle and nut drive which displaces said lockingcone and is formed so as to be drivable by said pinion shaft of said barvia a gear shaft.
 17. A trailer coupling as defined in claim 12; andfurther comprising a coupling piece for an electrical supply of atrailer, said coupling piece being associated with said bar and alsobeing displaceable.
 18. A trailer coupling as defined in claim 17,wherein said coupling piece is power-displaceable.
 19. A trailercoupling as defined in claim 12, wherein said bar has a drive which isoperable via an effective connection and has a switch disposable outsideof a passenger cell of a vehicle.
 20. A trailer coupling as defined inclaim 19, wherein said switch is disposable in a large compartment ofthe vehicle.